The requested advanced dual energy multidetector-row CT scanner has larger more sensitive x-ray detectors for more rapid, ultra-low dose (down to 0.1mSv) scans. It has advanced dual source multispectral CT capability with the availability of 90kVp/150 kVp dual x- ray sources to extend the sensitivity of multispectral CT that will provide marked improvement in ventilation imaging with xenon gas by providing images with reduced noise, higher contrast and spatial resolution and requiring lower concentrations of xenon gas, avoiding the unwanted anesthetic effects of the gas. The new scanner should also open up the possibility of imaging ventilation with krypton gas, thus avoiding the anesthetic effects all together. The enhanced contrast sensitivity along with the improved spectral separation of the delivered radiation will provide marked improvements in perfusion imaging using reduced iodine dosages with resultant decrease in beam hardening artifacts and allowing for multiple scans before reaching accepted limits of total iodine delivery. The enhanced multispectral imaging capability together with the elimination of confounding imaging artifacts such as are related to beam hardening and scatter allow for the accurate generation of virtual non-contrast anatomic CT scans, providing linkage between structure and function in a single low dose scan. It is expected that the enhanced spectral separation may allow for the simultaneous separation of xenon and iodine (or krypton and iodine) in addition to the generation of a virtual non-contrast image, allowing for the simultaneous imaging of ventilation, perfusion and structure in one ultra-low dose acquisition. In addition, the improved resolution of the scanner, it is hoped, will finall allow for the accurate determination of air wall structure, allowing for the assessment of airway wall remodeling serving as an important phenotype differentiating forms of COPD, severe vs. non-severe asthma, early evolution of bronchiectasis, etc. The scanner will additionally aid in our quantitative evaluation of osteoporosis, of interest as an important co-morbid condition in COPD, and it will aid in our development and evaluation of a broad range of genetically modified pigs for the study of lung disease.